foreach学习遇到的有关问题(细说php 兄弟连)
foreach学习遇到的问题(细说php 兄弟连)
书中代码如下
- PHP code
<!--Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--><?php $contact=array(1,14=>"高某","A公司","北京市",14=>"(010)98765432","[email protected]"); $num=0; foreach($contact as $value) { echo"在数组\$contact中第".$num."个元素是:$value<br>"; $num++; }?>
输出结果如下:
在数组$contact中第0个元素是:1
在数组$contact中第1个元素是:(010)98765432
在数组$contact中第2个元素是:A公司
在数组$contact中第3个元素是:北京市
在数组$contact中第4个元素是:[email protected]
小弟对于数组array存在困惑 其键与值的问题
第0个元素是1 这个我明白 那么第1个元素为什么会跳到电话号码呢?
14=>"高某"怎么算。。 然后是公司 北京市 邮箱 为什么会跳跃 不懂 求指点
ps : 此书输出语句居然是【在数组\$contact中第$num个元素是:$value
】 你没的 连接符都没有。
------解决方案--------------------
数组运行机制.
从左到右 按 键值生成 内容.无键值情况 则 按 数字顺序生成 键值。
以上
左到右的情况中 键值 为 14 的有2个
数组现排序 按插入情况排列
[0] = 1 (1)
[14] = 高某 (2) [15] = A公司 (3)
------解决方案--------------------
晕,你重复定义了
array(
14=>"高某",
14=>"(010)98765432"
);
自然就被(010)98765432,覆盖了
但是按照数组的排列14=>"高某",原来排在第二个,
所以14=>"(010)98765432"排在第二个
------解决方案--------------------
- PHP code
$contact = array( 1, 14 => "高某", "A公司", "北京市", 14 => "(010)98765432", "[email protected]");// 格式化打印出来,如下:echo '<pre class="brush:php;toolbar:false">';print_r($contact);/*Array( [0] => 1 [14] => (010)98765432 [15] => A公司 [16] => 北京市 [17] => [email protected])*/// 由此可以看出后面的“(010)98765432”将前面的“高某”覆盖了,这是为什么呢?因为php中同维度数组中不允许存在相同的键,你可以将键看成人的身份证号码,值看成是人的名字,名字有相同而身份证号不会有相同。之后数组变成如下:$contact=array(1,14=>"(010)98765432","A公司","北京市","[email protected]");//这个时候因为"A公司","北京市","[email protected]"这三个在键14的后面,那么它们的键不会再从1开始了,而是接着14开始,也就是15//咱们再看个例子(将"A公司"移动到1的后面):$contact=array(1,"A公司",14=>"(010)98765432","北京市","[email protected]");echo '<pre class="brush:php;toolbar:false">';print_r($contact);//结果输出如下:/*Array( [0] => 1 [1] => A公司 [14] => (010)98765432 [15] => 北京市 [16] => [email protected])*/<div class="clear"> </div>

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